Four wheel drive systems include Electronically Shifted and mechanically shifted four wheel drive systems. Certain of such electronically controlled systems may be shifted on the fly; meaning thereby there is a microprocessor that controls the shifting. Alternatively, there are Mechanical shift on the fly (MSOF) systems that operate with a manual lever and don't have an electronically controlled unit.
In an electronically controlled system, certain faults are detected and the microprocessor controls the shift device to take appropriate action in the presence of such faults. However, encoder faults are typically not addressed in a robust manner. It would be desirable to provide a system and method which adequately detects encoder faults in a robust manner.